Sony Xperia XCompact updated to latest Release 4.6.0.15 succesfully without problem during update.
It looks like the Internet sharing got broken with this update as it has gotten broken several times before with the updates. Fortunately there was some unofficial wpasupplicant fix somewhere, which will probably fix that problem once again.
Thank you Jollyboys and Thank you to that brilliant programmer who long long time ago made a patch that made it possible to run updates to this officially not supported Sony model. 